Day 5 part 2

5/5_2.py

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+#!/usr/bin/env python
+# 2021 - Advent Of Code - 5 part 2
+
+def parse_file(file):
+    horizontal_lines = []
+    vertical_lines = []
+    diagonal_lines = []
+    with open(file) as f:
+        for l in f.readlines():
+            p1, p2 = l.strip().split(' -> ')
+            strx1, stry1 = p1.split(',')
+            strx2, stry2 = p2.split(',')
+
+            # filter horizontal and vertical lines only
+            p1 = (int(strx1), int(stry1))
+            p2 = (int(strx2), int(stry2))
+            if strx1 == strx2:
+                vertical_lines.append([p1, p2])
+            elif stry1 == stry2:
+                horizontal_lines.append([p1, p2])
+            else:
+                diagonal_lines.append([p1, p2])
+
+    return horizontal_lines, vertical_lines, diagonal_lines
+
+
+def draw_horizontal(g, hline):
+
+    # print(f'drawing hline: {hline}')
+    if hline[0][0] < hline[1][0]:   # left -> right
+        start_point = hline[0]
+        end_point = hline[1]
+    else:
+        start_point = hline[1]
+        end_point = hline[0]
+
+    ly = start_point[1]
+    # print(f'drawing from {start_point[0]} to {end_point[0]}')
+    for lx in range(start_point[0], end_point[0]+1):
+        g[ly][lx] += 1
+
+
+def draw_vertical(g, vline):
+    # print(f'drawing vline: {vline}')
+    if vline[0][1] < vline[1][1]:   # up -> down
+        start_point = vline[0]
+        end_point = vline[1]
+    else:
+        start_point = vline[1]
+        end_point = vline[0]
+
+    lx = start_point[0]
+    # print(f'drawing from {start_point[0]} to {end_point[0]}')
+    for ly in range(start_point[1], end_point[1]+1):
+        g[ly][lx] += 1
+
+
+def draw_diagonal(g, dline):
+    x1 = dline[0][0]
+    y1 = dline[0][1]
+    x2 = dline[1][0]
+    y2 = dline[1][1]
+
+    hdir = 1
+    if x1 > x2:
+        hdir = -1
+
+    vdir = 1
+    if y1 > y2:
+        vdir = -1
+
+    lx = x1
+    ly = y1
+    for i in range(abs(x2-x1)+1):
+        g[ly][lx] += 1
+        lx += hdir
+        ly += vdir
+
+
+hlines, vlines, dlines = parse_file('input.txt')
+print(f'horizontal lines parsed: {len(hlines)}')
+print(f'vertical lines parsed: {len(vlines)}')
+print(f'diagonal lines parsed: {len(dlines)}')
+
+# detect size of the grid (assumed 1000x1000, but why not ;-) )
+maxx = 0
+maxy = 0
+for line in hlines + vlines + dlines:
+    startp = line[0]
+    endp = line[1]
+    if startp[0] > maxx:
+        maxx = startp[0]
+    if endp[0] > maxx:
+        maxx = endp[0]
+    if startp[1] > maxy:
+        maxy = startp[1]
+    if endp[1] > maxy:
+        maxy = endp[1]
+
+print(f'detected grid size: {maxx} x {maxy}')
+grid = [[0] * (maxx+1) for _ in range(maxy+1)]
+
+# draw
+for hl in hlines:
+    draw_horizontal(grid, hl)
+
+for vl in vlines:
+    draw_vertical(grid, vl)
+
+for dl in dlines:
+    draw_diagonal(grid, dl)
+
+# count points
+points = 0
+for y in range(maxy+1):
+    for x in range(maxx+1):
+        if grid[y][x] > 1:
+            points += 1
+
+print(f'There\'s {points} points with at least two lines')
+
+# bonus (or debug with the sample), draw the grid
+# print('  ', end='')
+# for y in range(maxy+1):
+#     print(y, end='')
+# print()
+#
+# for y in range(maxy+1):
+#     print(f'{y} ', end='')
+#     for x in range(maxx+1):
+#         if grid[y][x] == 0:
+#             print('.', end='')
+#         else:
+#             print(str(grid[y][x]), end='')
+#     print()